I've got a 2012 F-250 6.2 motor with 4:30 gears. Empty I get 14-16 in the summer and in the winter its down 1 or 2 mpg on average. I pull a 5th wheel that when loaded weighs out at 13,000lb. Pulling that I get mostly between 7-8mpg. When in hills I go to manual as I can anticipate hills sooner than the auto can, and downshift to maintain rpm. I tried the SCT tuner and was disappointed with the results. If your looking for a truck that seems to have more pep, than the tuner might be ok. I was looking for better mileage and when pulling realized no increase in mileage. Running empty maybe a little, but not enough to warrant the $300 plus dollars of the tuner. I put on 4,000 miles with the tuner, so thought I gave it a honest try. I've gone back to stock and like that better for shifting points. When I had the tuner I ran it in the tow mode all the time.